Realised niche changes in a native herbivore assemblage associated with the presence of livestock

Abstract

Habitat partitioning is a common ecological mechanism to avoid competition among coexisting species, and the introduction of new species into existing assemblages can increase competitive pressures. However, situations of species in allopatry and sympatry only differing in species presence but not in environmental conditions are scarce. Thus, discerning whether niche segregation arises from competition or from different habitat preferences is usually unfeasible.Here, we analyse species' habitat niches in an assemblage of native and introduced herbivores in southern Patagonia. We test if niche overlap is higher between native and domestic herbivores than among natives as expected from the relatively short time of coexistence, and we evaluate the effect of intra-and interspecific competition on niche breadth. We use a probabilistic multidimensional approach and null models to evaluate overlap and changes in niche dimensions.Overlap among native species is low as expected for species coexisting in evolutionary time. In native-domestic species pairs, niche overlap was higher than among natives, although showing some niche segregation indicating niche differentiation in ecological time. Moreover, the presence of domestic species was associated with niche narrowing of both native and introduced species, revealing interspecific density-dependent effects on their habitat niche during resource shortage periods.

Trait probability density (TPD): measuring functional diversity across scales based on TPD with R

“…(d) Changes in functional redundancy (expressed in relative terms) for single and multiple traits along the soil water content gradient. Indeed, although the TPD framework, as presented here, is primarily explained in terms of functional niche, similar concepts could be applied to other types of data, such as isotope ratios (Swanson et al 2015), climatic data (Blonder et al 2014), or habitat preferences (Traba et al 2015(Traba et al , 2017, as well as to traits of other taxonomic groups (Martello et al 2018); these are only some examples, but the number of potential applications of the framework is considerable. Ecology,Vol.…”

“…Combining information on redundancy and overlap-based dissimilarity between species and communities appears to be a promising approach in aiding the design of ecological restoration projects, including those intended to exclude invasive species (Laughlin 2014), or for the protection of species supporting specific ecosystem functions . Indeed, although the TPD framework, as presented here, is primarily explained in terms of functional niche, similar concepts could be applied to other types of data, such as isotope ratios (Swanson et al 2015), climatic data (Blonder et al 2014), or habitat preferences (Traba et al 2015(Traba et al , 2017, as well as to traits of other taxonomic groups (Martello et al 2018); these are only some examples, but the number of potential applications of the framework is considerable. With this in mind, we want to emphasize that we do not consider the TPD framework to be a definitive and closed collection of methods, but rather the first step towards a unified framework that accommodates the probabilistic and multidimensional nature of the functional facet of diversity.…”

Predator occurrence and perceived predation risk determine grouping behavior in guanaco (Lama guanicoe)

“…A detailed description of survey methodology is provided in Iranzo et al. (, ), and Traba, Iranzo, Carmona, and Malo ().…”

“…In addition, to reduce possible bias, the members of teams were rotated daily. A detailed description of survey methodology is provided in Iranzo et al (2013Iranzo et al ( , 2017, and Traba, Iranzo, Carmona, and Malo (2017).…”

Mapping extinction risk in the global functional spectra across the tree of life

“…We estimated TPD functions in the different functional spaces for the sets of species classified as Threatened or Non-threatened, as well as the TPD functions for all the species assessed by IUCN (including both threatened and non-threatened), using the same procedure described above. We then estimated the similarity between these TPD functions and the global spectra (the global TPD function considering also species not assessed by IUCN) as the overlap between the TPD functions (21,(68)(69)(70)(71). Compared to methods that consider exclusively the boundaries of the distributions (e.g.…”